1 files changed, 1779 insertions, 0 deletions

diff --git a/libblkid/probe.c b/libblkid/probe.c
new file mode 100644
index 000000000..77e8b860c
--- /dev/null
+++ b/libblkid/probe.c
@@ -0,0 +1,1779 @@
+/*
+ * Low-level libblkid probing API
+ *
+ * Copyright (C) 2008-2009 Karel Zak <kzak@redhat.com>
+ *
+ * This file may be redistributed under the terms of the
+ * GNU Lesser General Public License.
+ */
+
+/**
+ * SECTION: lowprobe
+ * @title: Low-level probing
+ * @short_description: low-level prober initialization
+ *
+ * The low-level probing routines always and directly read information from
+ * the selected (see blkid_probe_set_device()) device.
+ *
+ * The probing routines are grouped together into separate chains. Currently,
+ * the library provides superblocks, partitions and topology chains.
+ *
+ * The probing routines is possible to filter (enable/disable) by type (e.g.
+ * fstype "vfat" or partype "gpt") or by usage flags (e.g. BLKID_USAGE_RAID).
+ * These filters are per-chain. Note that always when you touch the chain
+ * filter the current probing position is reset and probing starts from
+ * scratch.  It means that the chain filter should not be modified during
+ * probing, for example in loop where you call blkid_do_probe().
+ *
+ * For more details see the chain specific documentation.
+ *
+ * The low-level API provides two ways how access to probing results.
+ *
+ *   1. The NAME=value (tag) interface. This interface is older and returns all data
+ *      as strings. This interface is generic for all chains.
+ *
+ *   2. The binary interfaces. These interfaces return data in the native formats.
+ *      The interface is always specific to the probing chain.
+ *
+ *  Note that the previous probing result (binary or NAME=value) is always
+ *  zeroized when a chain probing function is called. For example:
+ *
+ * <informalexample>
+ *   <programlisting>
+ *     blkid_probe_enable_partitions(pr, TRUE);
+ *     blkid_probe_enable_superblocks(pr, FALSE);
+ *
+ *     blkid_do_safeprobe(pr);
+ *   </programlisting>
+ * </informalexample>
+ *
+ * overwrites the previous probing result for the partitions chain, the superblocks
+ * result is not modified.
+ */
+
+/**
+ * SECTION: lowprobe-tags
+ * @title: Low-level tags
+ * @short_description: generic NAME=value interface.
+ *
+ * The probing routines inside the chain are mutually exclusive by default --
+ * only few probing routines are marked as "tolerant". The "tolerant" probing
+ * routines are used for filesystem which can share the same device with any
+ * other filesystem. The blkid_do_safeprobe() checks for the "tolerant" flag.
+ *
+ * The SUPERBLOCKS chain is enabled by default. The all others chains is
+ * necessary to enable by blkid_probe_enable_'CHAINNAME'(). See chains specific
+ * documentation.
+ *
+ * The blkid_do_probe() function returns a result from only one probing
+ * routine, and the next call from the next probing routine. It means you need
+ * to call the function in loop, for example:
+ *
+ * <informalexample>
+ *   <programlisting>
+ *	while((blkid_do_probe(pr) == 0)
+ *		... use result ...
+ *   </programlisting>
+ * </informalexample>
+ *
+ * The blkid_do_safeprobe() is the same as blkid_do_probe(), but returns only
+ * first probing result for every enabled chain. This function checks for
+ * ambivalent results (e.g. more "intolerant" filesystems superblocks on the
+ * device).
+ *
+ * The probing result is set of NAME=value pairs (the NAME is always unique).
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <ctype.h>
+#include <sys/types.h>
+#ifdef HAVE_LINUX_CDROM_H
+#include <linux/cdrom.h>
+#endif
+#ifdef HAVE_SYS_STAT_H
+#include <sys/stat.h>
+#endif
+#ifdef HAVE_ERRNO_H
+#include <errno.h>
+#endif
+#include <inttypes.h>
+#include <stdint.h>
+#include <stdarg.h>
+
+#ifdef HAVE_LIBUUID
+# include <uuid.h>
+#endif
+
+#include "blkidP.h"
+#include "all-io.h"
+
+/* chains */
+extern const struct blkid_chaindrv superblocks_drv;
+extern const struct blkid_chaindrv topology_drv;
+extern const struct blkid_chaindrv partitions_drv;
+
+/*
+ * All supported chains
+ */
+static const struct blkid_chaindrv *chains_drvs[] = {
+	[BLKID_CHAIN_SUBLKS] = &superblocks_drv,
+	[BLKID_CHAIN_TOPLGY] = &topology_drv,
+	[BLKID_CHAIN_PARTS] = &partitions_drv
+};
+
+static void blkid_probe_reset_vals(blkid_probe pr);
+static void blkid_probe_reset_buffer(blkid_probe pr);
+
+/**
+ * blkid_new_probe:
+ *
+ * Returns: a pointer to the newly allocated probe struct or NULL in case of error.
+ */
+blkid_probe blkid_new_probe(void)
+{
+	int i;
+	blkid_probe pr;
+
+	blkid_init_debug(0);
+	pr = calloc(1, sizeof(struct blkid_struct_probe));
+	if (!pr)
+		return NULL;
+
+	DBG(DEBUG_LOWPROBE, printf("allocate a new probe %p\n", pr));
+
+	/* initialize chains */
+	for (i = 0; i < BLKID_NCHAINS; i++) {
+		pr->chains[i].driver = chains_drvs[i];
+		pr->chains[i].flags = chains_drvs[i]->dflt_flags;
+		pr->chains[i].enabled = chains_drvs[i]->dflt_enabled;
+	}
+	INIT_LIST_HEAD(&pr->buffers);
+	return pr;
+}
+
+/*
+ * Clone @parent, the new clone shares all, but except:
+ *
+ *	- probing result
+ *	- bufferes if another device (or offset) is set to the prober
+ */
+blkid_probe blkid_clone_probe(blkid_probe parent)
+{
+	blkid_probe pr;
+
+	if (!parent)
+		return NULL;
+
+	DBG(DEBUG_LOWPROBE, printf("allocate a probe clone\n"));
+
+	pr = blkid_new_probe();
+	if (!pr)
+		return NULL;
+
+	pr->fd = parent->fd;
+	pr->off = parent->off;
+	pr->size = parent->size;
+	pr->devno = parent->devno;
+	pr->disk_devno = parent->disk_devno;
+	pr->blkssz = parent->blkssz;
+	pr->flags = parent->flags;
+	pr->parent = parent;
+
+	pr->flags &= ~BLKID_FL_PRIVATE_FD;
+
+	return pr;
+}
+
+
+
+/**
+ * blkid_new_probe_from_filename:
+ * @filename: device or regular file
+ *
+ * This function is same as call open(filename), blkid_new_probe() and
+ * blkid_probe_set_device(pr, fd, 0, 0).
+ *
+ * The @filename is closed by blkid_free_probe() or by the
+ * blkid_probe_set_device() call.
+ *
+ * Returns: a pointer to the newly allocated probe struct or NULL in case of
+ * error.
+ */
+blkid_probe blkid_new_probe_from_filename(const char *filename)
+{
+	int fd = -1;
+	blkid_probe pr = NULL;
+
+	if (!filename)
+		return NULL;
+
+	fd = open(filename, O_RDONLY|O_CLOEXEC);
+	if (fd < 0)
+		return NULL;
+
+	pr = blkid_new_probe();
+	if (!pr)
+		goto err;
+
+	if (blkid_probe_set_device(pr, fd, 0, 0))
+		goto err;
+
+	pr->flags |= BLKID_FL_PRIVATE_FD;
+	return pr;
+err:
+	if (fd >= 0)
+		close(fd);
+	blkid_free_probe(pr);
+	return NULL;
+}
+
+/**
+ * blkid_free_probe:
+ * @pr: probe
+ *
+ * Deallocates the probe struct, buffers and all allocated
+ * data that are associated with this probing control struct.
+ */
+void blkid_free_probe(blkid_probe pr)
+{
+	int i;
+
+	if (!pr)
+		return;
+
+	for (i = 0; i < BLKID_NCHAINS; i++) {
+		struct blkid_chain *ch = &pr->chains[i];
+
+		if (ch->driver->free_data)
+			ch->driver->free_data(pr, ch->data);
+		free(ch->fltr);
+	}
+
+	if ((pr->flags & BLKID_FL_PRIVATE_FD) && pr->fd >= 0)
+		close(pr->fd);
+	blkid_probe_reset_buffer(pr);
+	blkid_free_probe(pr->disk_probe);
+
+	DBG(DEBUG_LOWPROBE, printf("free probe %p\n", pr));
+	free(pr);
+}
+
+
+/*
+ * Removes chain values from probing result.
+ */
+void blkid_probe_chain_reset_vals(blkid_probe pr, struct blkid_chain *chn)
+{
+	int nvals = pr->nvals;
+	int i, x;
+
+	for (x = 0, i = 0; i < pr->nvals; i++) {
+		struct blkid_prval *v = &pr->vals[i];
+
+		if (v->chain != chn && x == i) {
+			x++;
+			continue;
+		}
+		if (v->chain == chn) {
+			--nvals;
+			continue;
+		}
+		memcpy(&pr->vals[x++], v, sizeof(struct blkid_prval));
+	}
+	pr->nvals = nvals;
+}
+
+static void blkid_probe_chain_reset_position(struct blkid_chain *chn)
+{
+	if (chn)
+		chn->idx = -1;
+}
+
+/*
+ * Copies chain values from probing result to @vals, the max size of @vals is
+ * @nvals and returns real number of values.
+ */
+int blkid_probe_chain_copy_vals(blkid_probe pr, struct blkid_chain *chn,
+		struct blkid_prval *vals, int nvals)
+{
+	int i, x;
+
+	for (x = 0, i = 0; i < pr->nvals && x < nvals; i++) {
+		struct blkid_prval *v = &pr->vals[i];
+
+		if (v->chain != chn)
+			continue;
+		memcpy(&vals[x++], v, sizeof(struct blkid_prval));
+	}
+	return x;
+}
+
+/*
+ * Appends values from @vals to the probing result
+ */
+void blkid_probe_append_vals(blkid_probe pr, struct blkid_prval *vals, int nvals)
+{
+	int i = 0;
+
+	while (i < nvals && pr->nvals < BLKID_NVALS) {
+		memcpy(&pr->vals[pr->nvals++], &vals[i++],
+				sizeof(struct blkid_prval));
+	}
+}
+
+static void blkid_probe_reset_vals(blkid_probe pr)
+{
+	memset(pr->vals, 0, sizeof(pr->vals));
+	pr->nvals = 0;
+}
+
+struct blkid_chain *blkid_probe_get_chain(blkid_probe pr)
+{
+	return pr->cur_chain;
+}
+
+void *blkid_probe_get_binary_data(blkid_probe pr, struct blkid_chain *chn)
+{
+	int rc, org_prob_flags;
+	struct blkid_chain *org_chn;
+
+	if (!pr || !chn)
+		return NULL;
+
+	/* save the current setting -- the binary API has to be completely
+	 * independent on the current probing status
+	 */
+	org_chn = pr->cur_chain;
+	org_prob_flags = pr->prob_flags;
+
+	pr->cur_chain = chn;
+	pr->prob_flags = 0;
+	chn->binary = TRUE;
+	blkid_probe_chain_reset_position(chn);
+
+	rc = chn->driver->probe(pr, chn);
+
+	chn->binary = FALSE;
+	blkid_probe_chain_reset_position(chn);
+
+	/* restore the original setting
+	 */
+	pr->cur_chain = org_chn;
+	pr->prob_flags = org_prob_flags;
+
+	if (rc != 0)
+		return NULL;
+
+	DBG(DEBUG_LOWPROBE,
+		printf("returning %s binary data\n", chn->driver->name));
+	return chn->data;
+}
+
+
+/**
+ * blkid_reset_probe:
+ * @pr: probe
+ *
+ * Zeroize probing results and resets the current probing (this has impact to
+ * blkid_do_probe() only). This function does not touch probing filters and
+ * keeps assigned device.
+ */
+void blkid_reset_probe(blkid_probe pr)
+{
+	int i;
+
+	if (!pr)
+		return;
+
+	blkid_probe_reset_vals(pr);
+	blkid_probe_set_wiper(pr, 0, 0);
+
+	pr->cur_chain = NULL;
+
+	for (i = 0; i < BLKID_NCHAINS; i++)
+		blkid_probe_chain_reset_position(&pr->chains[i]);
+}
+
+/***
+static int blkid_probe_dump_filter(blkid_probe pr, int chain)
+{
+	struct blkid_chain *chn;
+	int i;
+
+	if (!pr || chain < 0 || chain >= BLKID_NCHAINS)
+		return -1;
+
+	chn = &pr->chains[chain];
+
+	if (!chn->fltr)
+		return -1;
+
+	for (i = 0; i < chn->driver->nidinfos; i++) {
+		const struct blkid_idinfo *id = chn->driver->idinfos[i];
+
+		DBG(DEBUG_LOWPROBE, printf("%d: %s: %s\n",
+			i,
+			id->name,
+			blkid_bmp_get_item(chn->fltr, i)
+				? "disabled" : "enabled <--"));
+	}
+	return 0;
+}
+***/
+
+/*
+ * Returns properly initialized chain filter
+ */
+unsigned long *blkid_probe_get_filter(blkid_probe pr, int chain, int create)
+{
+	struct blkid_chain *chn;
+
+	if (!pr || chain < 0 || chain >= BLKID_NCHAINS)
+		return NULL;
+
+	chn = &pr->chains[chain];
+
+	/* always when you touch the chain filter all indexes are reset and
+	 * probing starts from scratch
+	 */
+	blkid_probe_chain_reset_position(chn);
+	pr->cur_chain = NULL;
+
+	if (!chn->driver->has_fltr || (!chn->fltr && !create))
+		return NULL;
+
+	if (!chn->fltr)
+		chn->fltr = calloc(1, blkid_bmp_nbytes(chn->driver->nidinfos));
+	else
+		memset(chn->fltr, 0, blkid_bmp_nbytes(chn->driver->nidinfos));
+
+	/* blkid_probe_dump_filter(pr, chain); */
+	return chn->fltr;
+}
+
+/*
+ * Generic private functions for filter setting
+ */
+int __blkid_probe_invert_filter(blkid_probe pr, int chain)
+{
+	size_t i;
+	struct blkid_chain *chn;
+
+	if (!pr)
+		return -1;
+
+	chn = &pr->chains[chain];
+
+	if (!chn->driver->has_fltr || !chn->fltr)
+		return -1;
+
+	for (i = 0; i < blkid_bmp_nwords(chn->driver->nidinfos); i++)
+		chn->fltr[i] = ~chn->fltr[i];
+
+	DBG(DEBUG_LOWPROBE, printf("probing filter inverted\n"));
+	/* blkid_probe_dump_filter(pr, chain); */
+	return 0;
+}
+
+int __blkid_probe_reset_filter(blkid_probe pr, int chain)
+{
+	return blkid_probe_get_filter(pr, chain, FALSE) ? 0 : -1;
+}
+
+int __blkid_probe_filter_types(blkid_probe pr, int chain, int flag, char *names[])
+{
+	unsigned long *fltr;
+	struct blkid_chain *chn;
+	size_t i;
+
+	fltr = blkid_probe_get_filter(pr, chain, TRUE);
+	if (!fltr)
+		return -1;
+
+	chn = &pr->chains[chain];
+
+	for (i = 0; i < chn->driver->nidinfos; i++) {
+		int has = 0;
+		const struct blkid_idinfo *id = chn->driver->idinfos[i];
+		char **n;
+
+		for (n = names; *n; n++) {
+			if (!strcmp(id->name, *n)) {
+				has = 1;
+				break;
+			}
+		}
+		if (flag & BLKID_FLTR_ONLYIN) {
+		       if (!has)
+				blkid_bmp_set_item(fltr, i);
+		} else if (flag & BLKID_FLTR_NOTIN) {
+			if (has)
+				blkid_bmp_set_item(fltr, i);
+		}
+	}
+
+	DBG(DEBUG_LOWPROBE,
+		printf("%s: a new probing type-filter initialized\n",
+		chn->driver->name));
+	/* blkid_probe_dump_filter(pr, chain); */
+	return 0;
+}
+
+unsigned char *blkid_probe_get_buffer(blkid_probe pr,
+				blkid_loff_t off, blkid_loff_t len)
+{
+	struct list_head *p;
+	struct blkid_bufinfo *bf = NULL;
+
+	if (pr->size <= 0)
+		return NULL;
+
+	if (pr->parent &&
+	    pr->parent->devno == pr->devno &&
+	    pr->parent->off <= pr->off &&
+	    pr->parent->off + pr->parent->size >= pr->off + pr->size) {
+		/*
+		 * This is a cloned prober and points to the same area as
+		 * parent. Let's use parent's buffers.
+		 *
+		 * Note that pr->off (and pr->parent->off) is always from the
+		 * beginig of the device.
+		 */
+		return blkid_probe_get_buffer(pr->parent,
+				pr->off + off - pr->parent->off, len);
+	}
+
+	list_for_each(p, &pr->buffers) {
+		struct blkid_bufinfo *x =
+				list_entry(p, struct blkid_bufinfo, bufs);
+
+		if (x->off <= off && off + len <= x->off + x->len) {
+			DBG(DEBUG_LOWPROBE,
+				printf("\treuse buffer: off=%jd len=%jd pr=%p\n",
+							x->off, x->len, pr));
+			bf = x;
+			break;
+		}
+	}
+	if (!bf) {
+		ssize_t ret;
+
+		if (blkid_llseek(pr->fd, pr->off + off, SEEK_SET) < 0)
+			return NULL;
+
+		/* allocate info and space for data by why call */
+		bf = calloc(1, sizeof(struct blkid_bufinfo) + len);
+		if (!bf)
+			return NULL;
+
+		bf->data = ((unsigned char *) bf) + sizeof(struct blkid_bufinfo);
+		bf->len = len;
+		bf->off = off;
+		INIT_LIST_HEAD(&bf->bufs);
+
+		DBG(DEBUG_LOWPROBE,
+			printf("\tbuffer read: off=%jd len=%jd pr=%p\n",
+				off, len, pr));
+
+		ret = read(pr->fd, bf->data, len);
+		if (ret != (ssize_t) len) {
+			free(bf);
+			return NULL;
+		}
+		list_add_tail(&bf->bufs, &pr->buffers);
+	}
+
+	return off ? bf->data + (off - bf->off) : bf->data;
+}
+
+
+static void blkid_probe_reset_buffer(blkid_probe pr)
+{
+	uint64_t read_ct = 0, len_ct = 0;
+
+	if (!pr || list_empty(&pr->buffers))
+		return;
+
+	DBG(DEBUG_LOWPROBE, printf("reseting probing buffers pr=%p\n", pr));
+
+	while (!list_empty(&pr->buffers)) {
+		struct blkid_bufinfo *bf = list_entry(pr->buffers.next,
+						struct blkid_bufinfo, bufs);
+		read_ct++;
+		len_ct += bf->len;
+		list_del(&bf->bufs);
+		free(bf);
+	}
+
+	DBG(DEBUG_LOWPROBE,
+		printf("buffers summary: %"PRIu64" bytes "
+			"by %"PRIu64" read() call(s)\n",
+			len_ct, read_ct));
+
+	INIT_LIST_HEAD(&pr->buffers);
+}
+
+/*
+ * Small devices need a special care.
+ */
+int blkid_probe_is_tiny(blkid_probe pr)
+{
+	return pr && (pr->flags & BLKID_FL_TINY_DEV);
+}
+
+/*
+ * CDROMs may fail when probed for RAID (last sector problem)
+ */
+int blkid_probe_is_cdrom(blkid_probe pr)
+{
+	return pr && (pr->flags & BLKID_FL_CDROM_DEV);
+}
+
+/**
+ * blkid_probe_set_device:
+ * @pr: probe
+ * @fd: device file descriptor
+ * @off: begin of probing area
+ * @size: size of probing area (zero means whole device/file)
+ *
+ * Assigns the device to probe control struct, resets internal buffers and
+ * resets the current probing.
+ *
+ * Returns: -1 in case of failure, or 0 on success.
+ */
+int blkid_probe_set_device(blkid_probe pr, int fd,
+		blkid_loff_t off, blkid_loff_t size)
+{
+	struct stat sb;
+
+	if (!pr)
+		return -1;
+
+	blkid_reset_probe(pr);
+	blkid_probe_reset_buffer(pr);
+
+	if ((pr->flags & BLKID_FL_PRIVATE_FD) && pr->fd >= 0)
+		close(pr->fd);
+
+	pr->flags &= ~BLKID_FL_PRIVATE_FD;
+	pr->flags &= ~BLKID_FL_TINY_DEV;
+	pr->flags &= ~BLKID_FL_CDROM_DEV;
+	pr->prob_flags = 0;
+	pr->fd = fd;
+	pr->off = off;
+	pr->size = 0;
+	pr->devno = 0;
+	pr->disk_devno = 0;
+	pr->mode = 0;
+	pr->blkssz = 0;
+	pr->wipe_off = 0;
+	pr->wipe_size = 0;
+	pr->wipe_chain = NULL;
+
+#if defined(POSIX_FADV_RANDOM) && defined(HAVE_POSIX_FADVISE)
+	/* Disable read-ahead */
+	posix_fadvise(fd, 0, 0, POSIX_FADV_RANDOM);
+#endif
+	if (fstat(fd, &sb))
+		goto err;
+
+	if (!S_ISBLK(sb.st_mode) && !S_ISCHR(sb.st_mode) && !S_ISREG(sb.st_mode))
+		goto err;
+
+	pr->mode = sb.st_mode;
+	if (S_ISBLK(sb.st_mode) || S_ISCHR(sb.st_mode))
+		pr->devno = sb.st_rdev;
+
+	if (size)
+		pr->size = size;
+	else {
+		if (S_ISBLK(sb.st_mode)) {
+			if (blkdev_get_size(fd, (unsigned long long *) &pr->size)) {
+				DBG(DEBUG_LOWPROBE, printf(
+					"failed to get device size\n"));
+				goto err;
+			}
+		} else if (S_ISCHR(sb.st_mode))
+			pr->size = 1;		/* UBI devices are char... */
+		else if (S_ISREG(sb.st_mode))
+			pr->size = sb.st_size;	/* regular file */
+
+		if (pr->off > pr->size)
+			goto err;
+
+		/* The probing area cannot be larger than whole device, pr->off
+		 * is offset within the device */
+		pr->size -= pr->off;
+	}
+
+	if (pr->size <= 1440 * 1024 && !S_ISCHR(sb.st_mode))
+		pr->flags |= BLKID_FL_TINY_DEV;
+
+#ifdef CDROM_GET_CAPABILITY
+	if (S_ISBLK(sb.st_mode) &&
+	    !blkid_probe_is_tiny(pr) &&
+	    blkid_probe_is_wholedisk(pr) &&
+	    ioctl(fd, CDROM_GET_CAPABILITY, NULL) >= 0)
+		pr->flags |= BLKID_FL_CDROM_DEV;
+#endif
+
+	DBG(DEBUG_LOWPROBE, printf("ready for low-probing, offset=%jd, size=%jd\n",
+				pr->off, pr->size));
+	DBG(DEBUG_LOWPROBE, printf("whole-disk: %s, regfile: %s\n",
+		blkid_probe_is_wholedisk(pr) ?"YES" : "NO",
+		S_ISREG(pr->mode) ? "YES" : "NO"));
+
+	return 0;
+err:
+	DBG(DEBUG_LOWPROBE,
+		printf("failed to prepare a device for low-probing\n"));
+	return -1;
+
+}
+
+int blkid_probe_get_dimension(blkid_probe pr,
+		blkid_loff_t *off, blkid_loff_t *size)
+{
+	if (!pr)
+		return -1;
+
+	*off = pr->off;
+	*size = pr->size;
+	return 0;
+}
+
+int blkid_probe_set_dimension(blkid_probe pr,
+		blkid_loff_t off, blkid_loff_t size)
+{
+	if (!pr)
+		return -1;
+
+	DBG(DEBUG_LOWPROBE, printf(
+		"changing probing area pr=%p: size=%llu, off=%llu "
+		"-to-> size=%llu, off=%llu\n",
+		pr,
+		(unsigned long long) pr->size,
+		(unsigned long long) pr->off,
+		(unsigned long long) size,
+		(unsigned long long) off));
+
+	pr->off = off;
+	pr->size = size;
+	pr->flags &= ~BLKID_FL_TINY_DEV;
+
+	if (pr->size <= 1440 * 1024 && !S_ISCHR(pr->mode))
+		pr->flags |= BLKID_FL_TINY_DEV;
+
+	blkid_probe_reset_buffer(pr);
+
+	return 0;
+}
+
+int blkid_probe_get_idmag(blkid_probe pr, const struct blkid_idinfo *id,
+			blkid_loff_t *offset, const struct blkid_idmag **res)
+{
+	const struct blkid_idmag *mag = NULL;
+	blkid_loff_t off = 0;
+
+	if (id)
+		mag = &id->magics[0];
+	if (res)
+		*res = NULL;
+
+	/* try to detect by magic string */
+	while(mag && mag->magic) {
+		unsigned char *buf;
+
+		off = (mag->kboff + (mag->sboff >> 10)) << 10;
+		buf = blkid_probe_get_buffer(pr, off, 1024);
+
+		if (buf && !memcmp(mag->magic,
+				buf + (mag->sboff & 0x3ff), mag->len)) {
+			DBG(DEBUG_LOWPROBE, printf(
+				"\tmagic sboff=%u, kboff=%ld\n",
+				mag->sboff, mag->kboff));
+			if (offset)
+				*offset = off + (mag->sboff & 0x3ff);
+			if (res)
+				*res = mag;
+			return 0;
+		}
+		mag++;
+	}
+
+	if (id && id->magics[0].magic)
+		/* magic string(s) defined, but not found */
+		return 1;
+
+	return 0;
+}
+
+static inline void blkid_probe_start(blkid_probe pr)
+{
+	if (pr) {
+		DBG(DEBUG_LOWPROBE, printf("%p: start probe\n", pr));
+		pr->cur_chain = NULL;
+		pr->prob_flags = 0;
+		blkid_probe_set_wiper(pr, 0, 0);
+	}
+}
+
+static inline void blkid_probe_end(blkid_probe pr)
+{
+	if (pr) {
+		DBG(DEBUG_LOWPROBE, printf("%p: end probe\n", pr));
+		pr->cur_chain = NULL;
+		pr->prob_flags = 0;
+		blkid_probe_set_wiper(pr, 0, 0);
+	}
+}
+
+/**
+ * blkid_do_probe:
+ * @pr: prober
+ *
+ * Calls probing functions in all enabled chains. The superblocks chain is
+ * enabled by default. The blkid_do_probe() stores result from only one
+ * probing function. It's necessary to call this routine in a loop to get
+ * results from all probing functions in all chains. The probing is reset
+ * by blkid_reset_probe() or by filter functions.
+ *
+ * This is string-based NAME=value interface only.
+ *
+ * <example>
+ *   <title>basic case - use the first result only</title>
+ *   <programlisting>
+ *
+ *	if (blkid_do_probe(pr) == 0) {
+ *		int nvals = blkid_probe_numof_values(pr);
+ *		for (n = 0; n < nvals; n++) {
+ *			if (blkid_probe_get_value(pr, n, &name, &data, &len) == 0)
+ *				printf("%s = %s\n", name, data);
+ *		}
+ *	}
+ *  </programlisting>
+ * </example>
+ *
+ * <example>
+ *   <title>advanced case - probe for all signatures</title>
+ *   <programlisting>
+ *
+ *	while (blkid_do_probe(pr) == 0) {
+ *		int nvals = blkid_probe_numof_values(pr);
+ *		...
+ *	}
+ *  </programlisting>
+ * </example>
+ *
+ * See also blkid_reset_probe().
+ *
+ * Returns: 0 on success, 1 when probing is done and -1 in case of error.
+ */
+int blkid_do_probe(blkid_probe pr)
+{
+	int rc = 1;
+
+	if (!pr)
+		return -1;
+
+	do {
+		struct blkid_chain *chn = pr->cur_chain;
+
+		if (!chn) {
+			blkid_probe_start(pr);
+			chn = pr->cur_chain = &pr->chains[0];
+		}
+		/* we go to the next chain only when the previous probing
+		 * result was nothing (rc == 1) and when the current chain is
+		 * disabled or we are at end of the current chain (chain->idx +
+		 * 1 == sizeof chain) or the current chain bailed out right at
+		 * the start (chain->idx == -1)
+		 */
+		else if (rc == 1 && (chn->enabled == FALSE ||
+				     chn->idx + 1 == (int) chn->driver->nidinfos ||
+				     chn->idx == -1)) {
+
+			size_t idx = chn->driver->id + 1;
+
+			if (idx < BLKID_NCHAINS)
+				chn = pr->cur_chain = &pr->chains[idx];
+			else {
+				blkid_probe_end(pr);
+				return 1;	/* all chains already probed */
+			}
+		}
+
+		chn->binary = FALSE;		/* for sure... */
+
+		DBG(DEBUG_LOWPROBE, printf("chain probe %s %s (idx=%d)\n",
+				chn->driver->name,
+				chn->enabled? "ENABLED" : "DISABLED",
+				chn->idx));
+
+		if (!chn->enabled)
+			continue;
+
+		/* rc: -1 = error, 0 = success, 1 = no result */
+		rc = chn->driver->probe(pr, chn);
+
+	} while (rc == 1);
+
+	return rc;
+}
+
+/**
+ * blkid_do_wipe:
+ * @pr: prober
+ * @dryrun: if TRUE then don't touch the device.
+ *
+ * This function erases the current signature detected by @pr. The @pr has to
+ * be open in O_RDWR mode, BLKID_SUBLKS_MAGIC or/and BLKID_PARTS_MAGIC flags
+ * has to be enabled.
+ *
+ * After successful signature removing the @pr prober will be moved one step
+ * back and the next blkid_do_probe() call will again call previously called
+ * probing function.
+ *
+ *  <example>
+ *  <title>wipe all filesystems or raids from the device</title>
+ *   <programlisting>
+ *      fd = open(devname, O_RDWR|O_CLOEXEC);
+ *      blkid_probe_set_device(pr, fd, 0, 0);
+ *
+ *      blkid_probe_enable_superblocks(pr, 1);
+ *      blkid_probe_set_superblocks_flags(pr, BLKID_SUBLKS_MAGIC);
+ *
+ *	while (blkid_do_probe(pr) == 0)
+ *		blkid_do_wipe(pr, FALSE);
+ *  </programlisting>
+ * </example>
+ *
+ * See also blkid_probe_step_back() if you cannot use this build-in wipe
+ * function, but you want to use libblkid probing as a source for wiping.
+ *
+ * Returns: 0 on success, and -1 in case of error.
+ */
+int blkid_do_wipe(blkid_probe pr, int dryrun)
+{
+	const char *off = NULL;
+	size_t len = 0;
+	loff_t offset, l;
+	char buf[BUFSIZ];
+	int fd, rc = 0;
+	struct blkid_chain *chn;
+
+	if (!pr)
+		return -1;
+
+	chn = pr->cur_chain;
+	if (!chn)
+		return -1;
+
+	switch (chn->driver->id) {
+	case BLKID_CHAIN_SUBLKS:
+		rc = blkid_probe_lookup_value(pr, "SBMAGIC_OFFSET", &off, NULL);
+		if (!rc)
+			rc = blkid_probe_lookup_value(pr, "SBMAGIC", NULL, &len);
+		break;
+	case BLKID_CHAIN_PARTS:
+		rc = blkid_probe_lookup_value(pr, "PTMAGIC_OFFSET", &off, NULL);
+		if (!rc)
+			rc = blkid_probe_lookup_value(pr, "PTMAGIC", NULL, &len);
+		break;
+	default:
+		return 0;
+	}
+
+	if (rc || len == 0 || off == NULL)
+		return 0;
+
+	offset = strtoll(off, NULL, 10);
+	fd = blkid_probe_get_fd(pr);
+	if (fd < 0)
+		return -1;
+
+	if (len > sizeof(buf))
+		len = sizeof(buf);
+
+	DBG(DEBUG_LOWPROBE, printf(
+	    "do_wipe [offset=0x%jx, len=%zd, chain=%s, idx=%d, dryrun=%s]\n",
+	    offset, len, chn->driver->name, chn->idx, dryrun ? "yes" : "not"));
+
+	l = lseek(fd, offset, SEEK_SET);
+	if (l == (off_t) -1)
+		return -1;
+
+	memset(buf, 0, len);
+
+	if (!dryrun && len) {
+		if (write_all(fd, buf, len))
+			return -1;
+		fsync(fd);
+		return blkid_probe_step_back(pr);
+	}
+
+	return 0;
+}
+
+/**
+ * blkid_probe_step_back():
+ * @pr: prober
+ *
+ * This function move pointer to the probing chain one step back -- it means
+ * that the previously used probing function will be called again in the next
+ * blkid_do_probe() call.
+ *
+ * This is necessary for example if you erase or modify on-disk superblock
+ * according to the current libblkid probing result.
+ *
+ * <example>
+ *  <title>wipe all superblock, but use libblkid only for probing</title>
+ *  <programlisting>
+ *      pr = blkid_new_probe_from_filename(devname);
+ *
+ *      blkid_probe_enable_superblocks(pr, 1);
+ *      blkid_probe_set_superblocks_flags(pr, BLKID_SUBLKS_MAGIC);
+ *
+ *	while (blkid_do_probe(pr) == 0) {
+ *		const char *ostr = NULL;
+ *		size_t len = 0;
+ *
+ *		// superblocks
+ *		if (blkid_probe_lookup_value(pr, "SBMAGIC_OFFSET", &ostr, NULL) == 0)
+ *			blkid_probe_lookup_value(pr, "SBMAGIC", NULL, &len);
+ *
+ *		// partition tables
+ *		if (len == 0 && blkid_probe_lookup_value(pr, "PTMAGIC_OFFSET", &ostr, NULL) == 0)
+ *			blkid_probe_lookup_value(pr, "PTMAGIC", NULL, &len);
+ *
+ *		if (!len || !str)
+ *			continue;
+ *
+ *		// convert ostr to the real offset by off = strtoll(ostr, NULL, 10);
+ *              // use your stuff to errase @len bytes at the @off
+ *              ....
+ *
+ *		// retry the last probing to check for backup superblocks ..etc.
+ *              blkid_probe_step_back(pr);
+ *	}
+ *  </programlisting>
+ * </example>
+ *
+ * Returns: 0 on success, and -1 in case of error.
+ */
+int blkid_probe_step_back(blkid_probe pr)
+{
+	struct blkid_chain *chn;
+
+	if (!pr)
+		return -1;
+
+	chn = pr->cur_chain;
+	if (!chn)
+		return -1;
+
+	blkid_probe_reset_buffer(pr);
+
+	if (chn->idx >= 0) {
+		chn->idx--;
+		DBG(DEBUG_LOWPROBE,
+			printf("step back: moving %s chain index to %d\n",
+			chn->driver->name,
+			chn->idx));
+	}
+
+	if (chn->idx == -1) {
+		/* blkid_do_probe() goes to the next chain if the index
+		 * of the current chain is -1, so we have to set the
+		 * chain pointer to the previous chain.
+		 */
+		size_t idx = chn->driver->id > 0 ? chn->driver->id - 1 : 0;
+
+		DBG(DEBUG_LOWPROBE, printf("step back: moving to previous chain\n"));
+
+		if (idx > 0)
+			pr->cur_chain = &pr->chains[idx];
+		else if (idx == 0)
+			pr->cur_chain = NULL;
+	}
+
+	return 0;
+}
+
+/**
+ * blkid_do_safeprobe:
+ * @pr: prober
+ *
+ * This function gathers probing results from all enabled chains and checks
+ * for ambivalent results (e.g. more filesystems on the device).
+ *
+ * This is string-based NAME=value interface only.
+ *
+ * Note about suberblocks chain -- the function does not check for filesystems
+ * when a RAID signature is detected.  The function also does not check for
+ * collision between RAIDs. The first detected RAID is returned. The function
+ * checks for collision between partition table and RAID signature -- it's
+ * recommended to enable partitions chain together with superblocks chain.
+ *
+ * Returns: 0 on success, 1 if nothing is detected, -2 if ambivalen result is
+ * detected and -1 on case of error.
+ */
+int blkid_do_safeprobe(blkid_probe pr)
+{
+	int i, count = 0, rc = 0;
+
+	if (!pr)
+		return -1;
+
+	blkid_probe_start(pr);
+
+	pr->prob_flags |= BLKID_PROBE_FL_IGNORE_BACKUP;
+
+	for (i = 0; i < BLKID_NCHAINS; i++) {
+		struct blkid_chain *chn;
+
+		chn = pr->cur_chain = &pr->chains[i];
+		chn->binary = FALSE;		/* for sure... */
+
+		DBG(DEBUG_LOWPROBE, printf("chain safeprobe %s %s\n",
+				chn->driver->name,
+				chn->enabled? "ENABLED" : "DISABLED"));
+
+		if (!chn->enabled)
+			continue;
+
+		blkid_probe_chain_reset_position(chn);
+
+		rc = chn->driver->safeprobe(pr, chn);
+
+		blkid_probe_chain_reset_position(chn);
+
+		/* rc: -2 ambivalent, -1 = error, 0 = success, 1 = no result */
+		if (rc < 0)
+			goto done;	/* error */
+		if (rc == 0)
+			count++;	/* success */
+	}
+
+done:
+	blkid_probe_end(pr);
+	if (rc < 0)
+		return rc;
+	return count ? 0 : 1;
+}
+
+/**
+ * blkid_do_fullprobe:
+ * @pr: prober
+ *
+ * This function gathers probing results from all enabled chains. Same as
+ * blkid_do_safeprobe() but does not check for collision between probing
+ * result.
+ *
+ * This is string-based NAME=value interface only.
+ *
+ * Returns: 0 on success, 1 if nothing is detected or -1 on case of error.
+ */
+int blkid_do_fullprobe(blkid_probe pr)
+{
+	int i, count = 0, rc = 0;
+
+	if (!pr)
+		return -1;
+
+	blkid_probe_start(pr);
+
+	for (i = 0; i < BLKID_NCHAINS; i++) {
+		struct blkid_chain *chn;
+
+		chn = pr->cur_chain = &pr->chains[i];
+		chn->binary = FALSE;		/* for sure... */
+
+		DBG(DEBUG_LOWPROBE, printf("chain fullprobe %s: %s\n",
+				chn->driver->name,
+				chn->enabled? "ENABLED" : "DISABLED"));
+
+		if (!chn->enabled)
+			continue;
+
+		blkid_probe_chain_reset_position(chn);
+
+		rc = chn->driver->probe(pr, chn);
+
+		blkid_probe_chain_reset_position(chn);
+
+		/* rc: -1 = error, 0 = success, 1 = no result */
+		if (rc < 0)
+			goto done;	/* error */
+		if (rc == 0)
+			count++;	/* success */
+	}
+
+done:
+	blkid_probe_end(pr);
+	if (rc < 0)
+		return rc;
+	return count ? 0 : 1;
+}
+
+/* same sa blkid_probe_get_buffer() but works with 512-sectors */
+unsigned char *blkid_probe_get_sector(blkid_probe pr, unsigned int sector)
+{
+	return pr ? blkid_probe_get_buffer(pr,
+			((blkid_loff_t) sector) << 9, 0x200) : NULL;
+}
+
+struct blkid_prval *blkid_probe_assign_value(
+			blkid_probe pr, const char *name)
+{
+	struct blkid_prval *v;
+
+	if (!name)
+		return NULL;
+	if (pr->nvals >= BLKID_NVALS)
+		return NULL;
+
+	v = &pr->vals[pr->nvals];
+	v->name = name;
+	v->chain = pr->cur_chain;
+	pr->nvals++;
+
+	DBG(DEBUG_LOWPROBE,
+		printf("assigning %s [%s]\n", name, v->chain->driver->name));
+	return v;
+}
+
+int blkid_probe_reset_last_value(blkid_probe pr)
+{
+	struct blkid_prval *v;
+
+	if (pr == NULL || pr->nvals == 0)
+		return -1;
+
+	v = &pr->vals[pr->nvals - 1];
+
+	DBG(DEBUG_LOWPROBE,
+		printf("un-assigning %s [%s]\n", v->name, v->chain->driver->name));
+
+	memset(v, 0, sizeof(struct blkid_prval));
+	pr->nvals--;
+
+	return 0;
+
+}
+
+int blkid_probe_set_value(blkid_probe pr, const char *name,
+		unsigned char *data, size_t len)
+{
+	struct blkid_prval *v;
+
+	if (len > BLKID_PROBVAL_BUFSIZ)
+		len = BLKID_PROBVAL_BUFSIZ;
+
+	v = blkid_probe_assign_value(pr, name);
+	if (!v)
+		return -1;
+
+	memcpy(v->data, data, len);
+	v->len = len;
+	return 0;
+}
+
+int blkid_probe_vsprintf_value(blkid_probe pr, const char *name,
+		const char *fmt, va_list ap)
+{
+	struct blkid_prval *v;
+	ssize_t len;
+
+	v = blkid_probe_assign_value(pr, name);
+	if (!v)
+		return -1;
+
+	len = vsnprintf((char *) v->data, sizeof(v->data), fmt, ap);
+
+	if (len <= 0 || (size_t) len >= sizeof(v->data)) {
+		blkid_probe_reset_last_value(pr);
+		return -1;
+	}
+	v->len = len + 1;
+	return 0;
+}
+
+int blkid_probe_sprintf_value(blkid_probe pr, const char *name,
+		const char *fmt, ...)
+{
+	int rc;
+	va_list ap;
+
+	va_start(ap, fmt);
+	rc = blkid_probe_vsprintf_value(pr, name, fmt, ap);
+	va_end(ap);
+
+	return rc;
+}
+
+int blkid_probe_set_magic(blkid_probe pr, blkid_loff_t offset,
+			size_t len, unsigned char *magic)
+{
+	int rc = 0;
+	struct blkid_chain *chn = blkid_probe_get_chain(pr);
+
+	if (!chn || !magic || !len || chn->binary)
+		return 0;
+
+	switch (chn->driver->id) {
+	case BLKID_CHAIN_SUBLKS:
+		if (!(chn->flags & BLKID_SUBLKS_MAGIC))
+			return 0;
+		rc = blkid_probe_set_value(pr, "SBMAGIC", magic, len);
+		if (!rc)
+			rc = blkid_probe_sprintf_value(pr,
+					"SBMAGIC_OFFSET", "%llu", (unsigned long long)offset);
+		break;
+	case BLKID_CHAIN_PARTS:
+		if (!(chn->flags & BLKID_PARTS_MAGIC))
+			return 0;
+		rc = blkid_probe_set_value(pr, "PTMAGIC", magic, len);
+		if (!rc)
+			rc = blkid_probe_sprintf_value(pr,
+					"PTMAGIC_OFFSET", "%llu", (unsigned long long)offset);
+		break;
+	default:
+		break;
+	}
+
+	return rc;
+}
+
+/**
+ * blkid_probe_get_devno:
+ * @pr: probe
+ *
+ * Returns: block device number, or 0 for regular files.
+ */
+dev_t blkid_probe_get_devno(blkid_probe pr)
+{
+	return pr->devno;
+}
+
+/**
+ * blkid_probe_get_wholedisk_devno:
+ * @pr: probe
+ *
+ * Returns: device number of the wholedisk, or 0 for regular files.
+ */
+dev_t blkid_probe_get_wholedisk_devno(blkid_probe pr)
+{
+	if (!pr->disk_devno) {
+		dev_t devno, disk_devno = 0;
+
+		devno = blkid_probe_get_devno(pr);
+		if (!devno)
+			return 0;
+
+		 if (blkid_devno_to_wholedisk(devno, NULL, 0, &disk_devno) == 0)
+			pr->disk_devno = disk_devno;
+	}
+	return pr->disk_devno;
+}
+
+/**
+ * blkid_probe_is_wholedisk:
+ * @pr: probe
+ *
+ * Returns: 1 if the device is whole-disk or 0.
+ */
+int blkid_probe_is_wholedisk(blkid_probe pr)
+{
+	dev_t devno, disk_devno;
+
+	devno = blkid_probe_get_devno(pr);
+	if (!devno)
+		return 0;
+
+	disk_devno = blkid_probe_get_wholedisk_devno(pr);
+	if (!disk_devno)
+		return 0;
+
+	return devno == disk_devno;
+}
+
+blkid_probe blkid_probe_get_wholedisk_probe(blkid_probe pr)
+{
+	dev_t disk;
+
+	if (blkid_probe_is_wholedisk(pr))
+		return NULL;			/* this is not partition */
+
+	if (pr->parent)
+		/* this is cloned blkid_probe, use parent's stuff */
+		return blkid_probe_get_wholedisk_probe(pr->parent);
+
+	disk = blkid_probe_get_wholedisk_devno(pr);
+
+	if (pr->disk_probe && pr->disk_probe->devno != disk) {
+		/* we have disk prober, but for another disk... close it */
+		blkid_free_probe(pr->disk_probe);
+		pr->disk_probe = NULL;
+	}
+
+	if (!pr->disk_probe) {
+		/* Open a new disk prober */
+		char *disk_path = blkid_devno_to_devname(disk);
+
+		if (!disk_path)
+			return NULL;
+
+		DBG(DEBUG_LOWPROBE, printf("allocate a wholedisk probe\n"));
+
+		pr->disk_probe = blkid_new_probe_from_filename(disk_path);
+
+		free(disk_path);
+
+		if (!pr->disk_probe)
+			return NULL;	/* ENOMEM? */
+	}
+
+	return pr->disk_probe;
+}
+
+/**
+ * blkid_probe_get_size:
+ * @pr: probe
+ *
+ * This function returns size of probing area as defined by blkid_probe_set_device().
+ * If the size of the probing area is unrestricted then this function returns
+ * the real size of device. See also blkid_get_dev_size().
+ *
+ * Returns: size in bytes or -1 in case of error.
+ */
+blkid_loff_t blkid_probe_get_size(blkid_probe pr)
+{
+	return pr ? pr->size : -1;
+}
+
+/**
+ * blkid_probe_get_offset:
+ * @pr: probe
+ *
+ * This function returns offset of probing area as defined by blkid_probe_set_device().
+ *
+ * Returns: offset in bytes or -1 in case of error.
+ */
+blkid_loff_t blkid_probe_get_offset(blkid_probe pr)
+{
+	return pr ? pr->off : -1;
+}
+
+/**
+ * blkid_probe_get_fd:
+ * @pr: probe
+ *
+ * Returns: file descriptor for assigned device/file or -1 in case of error.
+ */
+int blkid_probe_get_fd(blkid_probe pr)
+{
+	return pr ? pr->fd : -1;
+}
+
+/**
+ * blkid_probe_get_sectorsize:
+ * @pr: probe or NULL (for NULL returns 512)
+ *
+ * Returns: block device logical sector size (BLKSSZGET ioctl, default 512).
+ */
+unsigned int blkid_probe_get_sectorsize(blkid_probe pr)
+{
+	if (!pr)
+		return DEFAULT_SECTOR_SIZE;  /*... and good luck! */
+
+	if (pr->blkssz)
+		return pr->blkssz;
+
+	if (S_ISBLK(pr->mode) &&
+	    blkdev_get_sector_size(pr->fd, (int *) &pr->blkssz) == 0)
+		return pr->blkssz;
+
+	pr->blkssz = DEFAULT_SECTOR_SIZE;
+	return pr->blkssz;
+}
+
+/**
+ * blkid_probe_get_sectors:
+ * @pr: probe
+ *
+ * Returns: 512-byte sector count or -1 in case of error.
+ */
+blkid_loff_t blkid_probe_get_sectors(blkid_probe pr)
+{
+	return pr ? pr->size >> 9 : -1;
+}
+
+/**
+ * blkid_probe_numof_values:
+ * @pr: probe
+ *
+ * Returns: number of values in probing result or -1 in case of error.
+ */
+int blkid_probe_numof_values(blkid_probe pr)
+{
+	if (!pr)
+		return -1;
+	return pr->nvals;
+}
+
+/**
+ * blkid_probe_get_value:
+ * @pr: probe
+ * @num: wanted value in range 0..N, where N is blkid_probe_numof_values() - 1
+ * @name: pointer to return value name or NULL
+ * @data: pointer to return value data or NULL
+ * @len: pointer to return value length or NULL
+ *
+ * Note, the @len returns length of the @data, including the terminating
+ * '\0' character.
+ *
+ * Returns: 0 on success, or -1 in case of error.
+ */
+int blkid_probe_get_value(blkid_probe pr, int num, const char **name,
+			const char **data, size_t *len)
+{
+	struct blkid_prval *v = __blkid_probe_get_value(pr, num);
+
+	if (!v)
+		return -1;
+	if (name)
+		*name = v->name;
+	if (data)
+		*data = (char *) v->data;
+	if (len)
+		*len = v->len;
+
+	DBG(DEBUG_LOWPROBE, printf("returning %s value\n", v->name));
+	return 0;
+}
+
+/**
+ * blkid_probe_lookup_value:
+ * @pr: probe
+ * @name: name of value
+ * @data: pointer to return value data or NULL
+ * @len: pointer to return value length or NULL
+ *
+ * Note, the @len returns length of the @data, including the terminating
+ * '\0' character.
+ *
+ * Returns: 0 on success, or -1 in case of error.
+ */
+int blkid_probe_lookup_value(blkid_probe pr, const char *name,
+			const char **data, size_t *len)
+{
+	struct blkid_prval *v = __blkid_probe_lookup_value(pr, name);
+
+	if (!v)
+		return -1;
+	if (data)
+		*data = (char *) v->data;
+	if (len)
+		*len = v->len;
+	return 0;
+}
+
+/**
+ * blkid_probe_has_value:
+ * @pr: probe
+ * @name: name of value
+ *
+ * Returns: 1 if value exist in probing result, otherwise 0.
+ */
+int blkid_probe_has_value(blkid_probe pr, const char *name)
+{
+	if (blkid_probe_lookup_value(pr, name, NULL, NULL) == 0)
+		return 1;
+	return 0;
+}
+
+struct blkid_prval *__blkid_probe_get_value(blkid_probe pr, int num)
+{
+	if (!pr || num < 0 || num >= pr->nvals)
+		return NULL;
+
+	return &pr->vals[num];
+}
+
+struct blkid_prval *__blkid_probe_lookup_value(blkid_probe pr, const char *name)
+{
+	int i;
+
+	if (!pr || !pr->nvals || !name)
+		return NULL;
+
+	for (i = 0; i < pr->nvals; i++) {
+		struct blkid_prval *v = &pr->vals[i];
+
+		if (v->name && strcmp(name, v->name) == 0) {
+			DBG(DEBUG_LOWPROBE, printf("returning %s value\n", v->name));
+			return v;
+		}
+	}
+	return NULL;
+}
+
+
+/* converts DCE UUID (uuid[16]) to human readable string
+ * - the @len should be always 37 */
+#ifdef HAVE_LIBUUID
+void blkid_unparse_uuid(const unsigned char *uuid, char *str,
+			size_t len __attribute__((__unused__)))
+{
+	uuid_unparse(uuid, str);
+}
+#else
+void blkid_unparse_uuid(const unsigned char *uuid, char *str, size_t len)
+{
+	snprintf(str, len,
+		"%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
+		uuid[0], uuid[1], uuid[2], uuid[3],
+		uuid[4], uuid[5],
+		uuid[6], uuid[7],
+		uuid[8], uuid[9],
+		uuid[10], uuid[11], uuid[12], uuid[13], uuid[14],uuid[15]);
+}
+#endif
+
+
+/* Removes whitespace from the right-hand side of a string (trailing
+ * whitespace).
+ *
+ * Returns size of the new string (without \0).
+ */
+size_t blkid_rtrim_whitespace(unsigned char *str)
+{
+	size_t i = strlen((char *) str);
+
+	while (i--) {
+		if (!isspace(str[i]))
+			break;
+	}
+	str[++i] = '\0';
+	return i;
+}
+
+/* Removes whitespace from the left-hand side of a string.
+ *
+ * Returns size of the new string (without \0).
+ */
+size_t blkid_ltrim_whitespace(unsigned char *str)
+{
+	size_t len;
+	unsigned char *p;
+
+	for (p = str; p && isspace(*p); p++);
+
+	len = strlen((char *) p);
+
+	if (len && p > str)
+		memmove(str, p, len + 1);
+
+	return len;
+}
+/*
+ * Some mkfs-like utils wipe some parts (usually begin) of the device.
+ * For example LVM (pvcreate) or mkswap(8). This information could be used
+ * for later resolution to conflicts between superblocks.
+ *
+ * For example we found valid LVM superblock, LVM wipes 8KiB at the begin of
+ * the device. If we found another signature (for example MBR) within the
+ * wiped area then the signature has been added later and LVM superblock
+ * should be ignore.
+ *
+ * Note that this heuristic is not 100% reliable, for example "pvcreate --zero
+ * n" allows to keep the begin of the device unmodified. It's probably better
+ * to use this heuristic for conflicts between superblocks and partition tables
+ * than for conflicts between filesystem superblocks -- existence of unwanted
+ * partition table is very unusual, because PT is pretty visible (parsed and
+ * interpreted by kernel).
+ *
+ * Note that we usually expect only one signature on the device, it means that
+ * we have to remember only one wiped area from previously successfully
+ * detected signature.
+ *
+ * blkid_probe_set_wiper() -- defines wiped area (e.g. LVM)
+ * blkid_probe_use_wiper() -- try to use area (e.g. MBR)
+ *
+ * Note that there is not relation between _wiper and blkid_to_wipe().
+ *
+ */
+void blkid_probe_set_wiper(blkid_probe pr, blkid_loff_t off, blkid_loff_t size)
+{
+	struct blkid_chain *chn;
+
+	if (!pr)
+		return;
+
+	if (!size) {
+		DBG(DEBUG_LOWPROBE, printf("zeroize wiper\n"));
+		pr->wipe_size = pr->wipe_off = 0;
+		pr->wipe_chain = NULL;
+		return;
+	}
+
+	chn = pr->cur_chain;
+
+	if (!chn || !chn->driver ||
+	    chn->idx < 0 || (size_t) chn->idx >= chn->driver->nidinfos)
+		return;
+
+	pr->wipe_size = size;
+	pr->wipe_off = off;
+	pr->wipe_chain = chn;
+
+	DBG(DEBUG_LOWPROBE,
+		printf("wiper set to %s::%s off=%jd size=%jd\n",
+			chn->driver->name,
+			chn->driver->idinfos[chn->idx]->name,
+			pr->wipe_off, pr->wipe_size));
+	return;
+}
+
+/*
+ * Returns 1 if the <@off,@size> area was wiped
+ */
+int blkid_probe_is_wiped(blkid_probe pr, struct blkid_chain **chn,
+		     blkid_loff_t off, blkid_loff_t size)
+{
+	if (!pr || !size)
+		return 0;
+
+	if (pr->wipe_off <= off && off + size <= pr->wipe_off + pr->wipe_size) {
+		if (chn)
+			*chn = pr->wipe_chain;
+		return 1;
+	}
+	return 0;
+}
+
+/*
+ *  Try to use any area -- if the area has been previously wiped then the
+ *  previous probing result should be ignored (reseted).
+ */
+void blkid_probe_use_wiper(blkid_probe pr, blkid_loff_t off, blkid_loff_t size)
+{
+	struct blkid_chain *chn = NULL;
+
+	if (blkid_probe_is_wiped(pr, &chn, off, size) && chn) {
+		DBG(DEBUG_LOWPROBE, printf("previously wiped area modified "
+				       " -- ignore previous results\n"));
+		blkid_probe_set_wiper(pr, 0, 0);
+		blkid_probe_chain_reset_vals(pr, chn);
+	}
+}
+
+int blkid_probe_ignore_backup(blkid_probe pr)
+{
+	return pr && (pr->prob_flags & BLKID_PROBE_FL_IGNORE_BACKUP);
+}